Powerlines

From: Daniel T. Burrows <danburrows_at_mindspring.com>
Date: Mon Apr 26 21:33:59 1999

>"Daniel T. Burrows" <danburrows_at_mindspring.com> wrote:
>> Close but not quite right. For single phase installations the power
company
>> supplies 2 hots and neutral. This is a center tapped secondary and the
>> neutral is earthed at the service entrance.
>
>No, for split-phase, the power company does not "supply" a neutral from the
>distribution system. The neutral is *only* tied to the center tap of the
>secondary and to ground. It is not tied to anything on the primary side of
>the transformer; that would be bad.


That is what I was trying to decsribe above.

>> The primary of this transformer
>> is fed from only 1 high voltage phase.
>
>I don't believe this; it doesn't match the descriptions I've read
elsewhere.
>I've always seen it shown in diagrams with the primary connected across two
>phases of the three-phase. Otherwise you need a high-current return path
>somewhere else.

Take a close look at rural areas and there is only 1 High voltage line
present.
It is fed to the HT input of all the pole transformers.


>To even the loading of the phases, the transformers for split-phase service
>have their primaries distributed between the three possible combinations of
>the three phases.

When there are 3 phases available that sometimes is the case. Look closely
at the pole transformers and in most cases when there are 2 or more
transformers mounted on 1 pole there is only 1 HT input to each transformer.
If it were between phases there would be 2 HT inputs.

Dan
Received on Mon Apr 26 1999 - 21:33:59 BST